The invention provides a method and associated apparatus for detecting and analyzing reactions of fluorescently marked materials on a single substrate surface.
Certain macromolecules are known to interact and bind to other molecules having a very specific three-dimensional spatial and electronic distribution. Any large molecule having such specificity can be considered a target. The various molecules that targets selectively bind to are known as probes.
Methods and devices for detecting fluorescently marked targets on devices are known. Generally, the devices includes a microscope and a monochromatic or polychromatic light source for directing light at a substrate. A photon counter detects fluorescence from the substrate, while an x-y translation stage varies the location of the substrate. A computer controls the movement of the x-y translation table and data collection. Such devices are discussed in, for example, U.S. Pat No. 5,143,854 (Pirrung et al.) incorporated herein by reference for all purposes. See also PCT WO 92/10092 also incorporated herein by reference for all purposes.
Light from the light source is focused at the substrate surface by manually adjusting the microscope. Manual adjustment is, on occasion, time consuming and inconvenient. Moreover, due to inherent imperfections present in the x-y translation table and substrate, there is a possibility that the substrate will be out of focus as it is moved from one region to another. As a result, the data collected may be misrepresented.
Also, temperature sometimes impact a chemical reaction between targets and probes. Generally, targets are more active or form stronger bonds at lower temperatures while the converse is true at higher temperatures. However, if the temperature is too low, the binding affinity of the target may become excessively strong, thus causing target to bind with complements (matches) as well as non-compliments (mismatches). Hence, the ability to control temperature may affect optimum binding between the targets and probes while minimizing mismatches.
In addition, the microscope detection devices are uneconomical to use. Typically, these devices incorporates the use of a microscope, and a multichannel scaler, both of which are costly.
From the above, it is apparent that an improved method and apparatus for detecting fluorescently labeled targets on a substrate is desired.